8,560 research outputs found
B_s to K^(*)0 \bar K^(*)0 decays: the golden channels for new physics searches
We point out that time-dependent CP asymmetries in B_s to K^{*0} \bar K^{*0}
decays probe the presence of new physics in b to s transitions with an
unprecedented theoretical accuracy. We show that, contrary to the case of B_d
to phi K_S, it is possible to obtain a model-independent prediction for the
coefficient S(B_s to K^{*0} \bar K^{*0}) in the Standard Model. We give an
estimate of the experimental precision achievable with the next generation of B
physics experiments. We also discuss how this approach can be extended to the
case of B_s to \bar K^{*0} K^0, B_s to K^{*0} \bar K^0 and B_s to K^0 \bar K^0
decays and the different experimental challenges for these channels.Comment: 4 pages, 1 figure. v2: Corrected dependence on CKM angles, expanded
discussion of multiple polarizations, conclusions strengthened. Final version
to appear in PR
Preserving Information from the Beginning to the End of time in a Robertson-Walker Spacetime
Preserving information stored in a physical system subjected to noise can be
modeled in a communication-theoretic paradigm, in which storage and retrieval
correspond to an input encoding and output decoding, respectively. The encoding
and decoding are then constructed in such a way as to protect against the
action of a given noisy quantum channel. This paper considers the situation in
which the noise is not due to technological imperfections, but rather to the
physical laws governing the evolution of the universe. In particular, we
consider the dynamics of quantum systems under a 1+1 Robertson-Walker spacetime
and find that the noise imparted to them is equivalent to the well known
amplitude damping channel. Since one might be interested in preserving both
classical and quantum information in such a scenario, we study trade-off coding
strategies and determine a region of achievable rates for the preservation of
both kinds of information. For applications beyond the physical setting studied
here, we also determine a trade-off between achievable rates of classical and
quantum information preservation when entanglement assistance is available.Comment: 19 pages, 3 figures. Presentation updated, matches the published
versio
Two Body B Decays, Factorization and LambdaQCD/mb Corrections
By using the recent experimental measurements of B -> pi pi and B -> K pi
branching ratios, we find that the amplitudes computed at the leading order of
the LambdaQCD/mb expansion disagree with the observed BRs, even taking into
account the uncertainties of the input parameters. Beyond the leading order,
Charming and GIM penguins allow to reconcile the theoretical predictions with
the data. Because of these large effects, we conclude, however, that it is not
possible, with the present theoretical and experimental accuracy, to determine
the CP violation angle gamma from these decays. We compare our results with
those obtained with the parametrization of the chirally enhanced
non-perturbative contributions by BBNS. We also predict large asymmetries for
several of the particle--antiparticle BRs, in particular BR(B+ -> K+ pi0),
BR(Bd -> K+ pi-) and BR(Bd -> pi+ pi-).Comment: 14 pages 3 figures uses aippro
Charming Penguins Saga
We briefly recall the main formulae for computing the B -> K pi branching
ratios within the "charming penguin" approach, present an updated fit to the
data, and explain why we believe that, in general, these fits can hardly be
used to extract gamma.Comment: Invited talk at FPCP '02 given by M. Ciuchini, uses econfmacros.tex.
Final version with minor changes to appear in the proceeding
Squark-mediated Higgs+jets production at the LHC
We investigate possible scenarios of light-squark production at the LHC as a
new mechanism to produce Higgs bosons in association with jets. The study is
motivated by the SUSY search for H+jets events, performed by the CMS
collaboration on 8 and 13 TeV data using the razor variables. Two simplified
models are proposed to interpret the observations in this search. The
constraint from Run I and the implications for Run II and beyond are discussed
Penguin Contractions and Factorization in B -> K pi Decays
We study Lambda_{QCD}/m_B corrections to factorization in B -> K pi decays.
First, we analyze these decay channels within factorization, showing that,
irrespectively of the value of gamma, it is not possible to reproduce the
experimental data. Then, we discuss Lambda_{QCD}/m_B corrections to these
processes, and argue that there is a class of doubly Cabibbo enhanced
non-factorizable contributions, usually called charming penguins, that cannot
be neglected. Including these corrections, we obtain an excellent agreement
with experimental data. Furthermore, contrary to what is obtained with
factorization, we predict sizable rate asymmetries in B^\pm -> K^\pm \pi^0 and
B -> K^\pm pi^\mp.Comment: 4 pages, 3 figures. Talk given by L. Silvestrini at BCP4, Ise-Shima,
Japan, 18-23 Feb 200
Two-body nonleptonic B decays in the Standard Model and beyond
We briefly discuss the phenomenology of B to pi pi, B to K pi and B to phi K
decays in the Standard Model and in Supersymmetry.Comment: 7 pages, 2 figures, uses moriond.sty. Talk given by L. Silvestrini at
the XXXIXth Rencontres de Moriond on ElectroWeak Interactions and Unified
Theories, La Thuile, Aosta Valley, Italy, March 21st-28th 200
The tilt of the Fundamental Plane of Early-type galaxies: wavelength dependence
The photometric parameters R_e and mu_e of 74 early-type (E+S0+S0a) galaxies
in the Coma cluster are derived for the first time in the near IR H band. These
are used, coupled with measurements of the central velocity dispersion found in
the literature, to determine the H band Fundamental Plane (FP) relation of this
cluster. The same procedure is applied to previously available photometric data
in the B, V, r, I, and K bands, to perform a multi-wavelength study of the FP.
Because systematic uncertainties in the value of the FP parameters are
introduced both by the choice of the fitting algorithm, and by the presence of
statistical biases connected with the sample selection procedure, we emphasize
the importance of deriving the FP parameters in the six photometric bands using
an identical fitting algorithm, and appropriate corrections to eliminate the
effects of sample incompleteness. We find that the FP mu_e coefficient is
stable with wavelength, while the sigma coefficient increases significantly
with increasing wavelength, in agreement with an earlier result presented by
Pahre & Djorgovski. The slope of the FP relation, although changing with
wavelength, never approaches the virial theorem expectation. We also find that
the magnitude of the slope change can be entirely explained by the presence of
the well known relation between color and magnitude among early-type galaxies.
We conclude that the tilt of the Fundamental Plane is significant, and must be
due to some form of broken homology among early-type galaxies, while its
wavelength dependence derives from whatever mechanism (currently the preferred
one is the existence of a mass-metal content sequence) produces the
color-magnitude relation in those galaxies.Comment: 8 pages, 7 figures, 6 tables; table 3 should be printed in landscape
mode, and inserted into the text. Accepted for publication in MNRA
Investigating The Physics Case of Running a B-Factory at the Y(5S) Resonance
We discuss the physics case of a high luminosity B-Factory running at the
Y(5S) resonance. We show that the coherence of the B meson pairs is preserved
at this resonance, and that Bs can be well distinguished from Bd and charged B
mesons. These facts allow to cover the physics program of a traditional
B-Factory and, at the same time, to perform complementary measurements which
are not accessible at the Y(4S). In particular we show how, despite the
experimental limitations in performing time-dependent measurements of Bs
decays, the same experimental information can be extracted, in several cases,
from the determination of time-integrated observables. In addition, a few
examples of the potentiality in measuring rare Bs decays are given. Finally, we
discuss how the study of Bs meson will improve the constraints on New Physics
parameters in the Bs sector, in the context of the generalized Unitarity
Triangle analysis.Comment: 47 pages, 22 figure
Dust Attenuation in Late-Type Galaxies. I. Effects on Bulge and Disk Components
We present results of new Monte Carlo calculations made with the DIRTY code
of radiative transfer of stellar and scattered radiation for a dusty giant
late-type galaxy like the Milky Way, which illustrate the effect of the
attenuation of stellar light by internal dust on the integrated photometry of
the individual bulge and disk components. Here we focus on the behavior of the
attenuation function, the color excess, and the fraction of light scattered or
directly transmitted towards the outside observer as a function of the total
amount of dust and the inclination of the galaxy, and the structure of the
dusty interstellar medium (ISM) of the disk. We confirm that dust attenuation
produces qualitatively and quantitatively different effects on the integrated
photometry of bulge and disk, whatever the wavelength. In addition, we find
that the structure of the dusty ISM affects more sensitively the observed
magnitudes than the observed colors of both bulge and disk. Finally, we show
that the contribution of the scattered radiation to the total monochromatic
light received by the outside observer is significant, particularly at UV
wavelengths, even for a two-phase, clumpy, dusty ISM. Thus understanding dust
scattering properties is fundamental for the interpretation of extragalactic
observations in the rest-frame UV.Comment: 62 pages, 28 eps-figures, 1 table, accepted for publication in ApJ
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